Do electrons have volume

No. By definition, valence electrons are the furthest electrons from the nucleus in the atom. They are the electrons most easily removed from (or added to) the atom to create ions. A loophole to this answer might be to say that hydrogen and helium only have 1 and 2 electrons respectively so their valence electrons are close. That's a matter of perspective, as no electrons are really "close" to the nucleus to begin with. A typical comparison is to imagine a grape seed in the middle of a football stadium. The grape seed represents the nucleus, and an electron would be a speck of dust on the outside of the stadium. No. By definition, valence electrons are the furthest electrons from the nucleus in the atom. They are the electrons most easily removed from (or added to) the atom to create ions. A loophole to this answer might be to say that hydrogen and helium only have 1 and 2 electrons respectively so their valence electrons are close. That's a matter of perspective, as no electrons are really "close" to the nucleus to begin with. A typical comparison is to imagine a grape seed in the middle of a football stadium. The grape seed represents the nucleus, and an electron would be a speck of dust on the outside of the stadium.